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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 667 records · Page 37Linked to original sources
PubMed1995

The effects of antireflux therapy on pulmonary function in patients with severe gastroesophageal reflux disease. Department of Veterans Affairs Gastroesophageal Reflux Disease Study Group.

OBJECTIVES: Gastroesophageal reflux can induce bronchospasm, and antireflux therapy has been shown to improve pulmonary function in patients who have gastroesophageal reflux disease (GERD) associated with asthma. Our objective was to study the pulmonary effects of antireflux therapy in patients who had severe GERD without clinically apparent lung disease. METHODS: In a Department of Veterans Affairs Cooperative Study, patients who had complicated GERD without important lung disease were randomly assigned to receive one of three types of antireflux treatment, including two kinds of medical therapy and a surgical therapy. Patients had pulmonary function tests (PFTs), including total lung capacity, residual volume, forced vital capacity, forced expiratory volume in 1 s, maximal midexpiratory flow, and diffusing capacity for carbon monoxide. RESULTS: Two hundred forty-seven patients (243 men, four women; mean age 58 yr) entered the randomized trial, and 151 returned for PFTs at 1 yr. For the entire study group and for all three treatment groups, mean values for PFTs at 1 yr did not differ significantly from those at baseline. Even in subgroups of patients whose baseline PFTs were abnormal and whose esophagitis had healed completely, there were no significant changes in results of PFTs. CONCLUSIONS: For veteran patients with severe GERD and no obvious lung disease, 1 yr of antireflux therapy had no important effect on pulmonary function. These findings suggest that GERD is not commonly associated with inapparent, reversible pulmonary dysfunction.

Female↗
PubMed1995

The anti-lipid A monoclonal antibody E5 binds to rough gram-negative bacteria, fixes C3, and facilitates binding of bacterial immune complexes to both erythrocytes and monocytes.

Treatment of patients with septic shock using monoclonal antibodies (mAbs) to endotoxin is still controversial. Clinical trials of E5, one of the mAbs directed against the lipid A moiety of lipopolysaccharide (LPS), are currently in progress. The mechanisms of action of this, and other antibodies under clinical evaluation, are, however, poorly understood. In this study we examined in vitro the ways in which E5 interacted with Gram-negative bacteria, complement, erythrocytes and monocytes. By fluorescence-activated cell sorter (FACS) analysis we showed direct, dose-dependent binding of E5 to Escherichia coli (E. coli) and Salmonella minnesota (S. minnesota). Antibody binding to S. minnesota was enhanced by treatment with the beta-lactam antibiotic amoxycillin, but not by treatment with the aminoglycoside gentamicin. Immune complexes formed between E5 and both species of Gram-negative bacteria activated both classical and alternative complement pathways, but only in the case of S. minnesota did this facilitate binding to erythrocyte CR1 and monocyte CR3. Bacterial C3b and iC3b fixation by E5 was quantified using specific mAbs. These observations suggest that E5 may enhance bacterial clearance in several ways: (1) by facilitating direct complement fixation; (2) by facilitating the binding of opsonized bacteria to cells of the mononuclear phagocyte system; (3) by enabling bacteria to bind to erythrocyte CR1 (CD35), allowing safe carriage in the circulation to the fixed macrophages of the liver and spleen; (4) by acting synergistically with beta-lactam antibiotics.

Anti-Bacterial Agents↗
PubMed1995

Extensive regeneration in vitro by early embryonic neurons on immature and adult CNS tissue.

The failure of axon regeneration in the injured adult CNS has been ascribed to axon growth inhibitory molecules expressed by the resident glial cell populations, especially oligodendrocytes. Unlike their adult counterparts, however, early embryonic neurons are able to send lengthy axons through myelinated fiber tracts when transplanted into the adult brain. One explanation is that they have yet to express receptors for factors that inhibit the growth of older neurons. To test this possibility, we have used the cryoculture technique to study the regeneration of rat central and peripheral neurons, over a developmental period that encompasses the stages before, during, and after target contact, when cultured on either unmyelinated (neonatal) or myelinated (adult) optic nerve tissue sections. Early embryonic (days 14-15) retinal ganglion cells extended neurites on neonatal optic nerve, but few grew on adult optic nerve. In the case of early embryonic dorsal root ganglion neurons, however, neurite outgrowth on either neonatal optic nerve or on adult optic nerve was extensive. This response declined sharply with age. In contrast, neurite outgrowth by dorsal root ganglion neurons on laminin substrata remained relatively constant (> 80% extended neurites) over the same period. This suggests that (a) inhibition of neurite outgrowth within the optic nerve is mediated not only by oligodendrocytes, but also by molecules expressed prior to the onset of myelination; (b) neurons acquire receptors for these inhibitors only late in embryonic development; (c) differences exist between developing central and peripheral neurons in the response to myelin-associated axon-growth inhibitors.

Animals↗
PubMed1995

[Antigenic types of circulating rotavirus in children with acute diarrhea in Santiago de Chile].

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. The aim of this study was to characterize the VP7 and VP4 antigenic types circulating in different hospital areas of Santiago, Chile, over different time periods. Between April 1993 and April 1994 a total of 1206 stool samples were obtained from children consulting for acute no bloody diarrhea in 5 hospitals representative of the 5 major health areas of Santiago. In addition, 256 rotavirus positive samples, obtained from children with acute diarrhea consulting in the north health area of Santiago between 1985-1987 were studied. All samples were processed for rotavirus by an ELISA and all rotavirus positive samples were VP7 typed (types G1-G4) by a monoclonal antibody based ELISA. 50 rotavirus positive samples were selected for VP4 typing by PCR (types P1-P4). A total of 782 rotavirus positive samples were obtained of which 618 (79%) were typable for one specific VP7 type. VP7 type G1 represented 63% of the rotavirus positive samples and predominated in all areas evaluated throughout the entire period of observation. VP7 type G2 represented 13% of rotavirus samples, following G1 in predominance. G2 types decreased progressively in all areas in both study periods. G4 types were detected mainly during 1985-1987, and G3 types have so far not been detected. Preliminary analysis of VP4 types suggests that P1 types are predominant and closely associated with VP7 G1 type. These results are relevant for the adoption of appropriate preventive strategies for rotavirus infection, specifically aimed to the development of effective vaccines.

Acute Disease↗
PubMed1995

[Monozygotic triplet pregnancy after transfer of frozen embryos].

We report a case of monozygotic triplet pregnancy after transfer of 3 frozen thawed embryos. The pregnancy ended by the birth of 3 healthy normal boys and all the analysis showed that it was really a monochorionic triamniotic triplet pregnancy, that as far as we know is the first reported one induced by frozen thawed technics. We shall discuss: the etiology of monozygotic pregnancies after IVF; the sonographic diagnosis of placentation; the obstetrical care which allowed the birth of 3 healthy normal boys.

Adult↗
PubMed1994

Protective effect of 55- but not 75-kD soluble tumor necrosis factor receptor-immunoglobulin G fusion proteins in an animal model of gram-negative sepsis.

The aim of this study was to compare the ability of both a 55- and 75-kD soluble tumor necrosis factor receptor immunoglobulin G fusion protein (sTNFR-IgG) in protecting against death in a murine model of gram-negative sepsis. Pretreatment with 250 micrograms of the p75 construct delayed but did not avert death in this model, reducing peak bioactive TNF-alpha levels after infection from 76.4 ng ml-1 in control mice to 4.7 ng ml-1 in the treated group (p < 0.05, two-sample t test). However, these low levels of bioactive TNF-alpha persisted in the p75 fusion protein-treated animals compared with the controls and were sufficient to mediate delayed death. In contrast, pretreatment with 200 micrograms of the p55 sTNFR-IgG gave excellent protection against death with complete neutralization of circulating TNF. Studies of the binding of TNF-alpha with the soluble TNFR fusion proteins showed that the p75 fusion construct exchanges bound TNF-alpha about 50-100-fold faster than the p55 fusion protein. Thus, although both fusion proteins in equilibrium bind TNF-alpha with high affinity, the TNF-alpha p55 fusion protein complex is kinetically more stable than the p75 fusion construct, which thus acts as a TNF carrier. The persistent release of TNF-alpha from the p75 fusion construct limits its therapeutic effect in this model of sepsis.

Animals↗
PubMed1994

Isolation and envelope sequence of a highly divergent HIV-1 isolate: definition of a new HIV-1 group.

We report here the isolation and envelope sequence of a divergent HIV-1 isolate from a French woman with AIDS. This virus, HIV-1VAU, is closely related to the recently described Cameroonian viral isolates HIV-1ANT70 and HIV-1MVP5180, until now designated HIV-1 subtype O. Phylogenetic analysis reveals that the three viruses are equidistant from one another and that their mutual divergence is similar to what has been reported between the more conventional HIV-1 subtypes. Therefore, these three viruses could be included in a new viral group, HIV-1 group O (outgroup), distinct from the cluster of other HIV-1 isolates, which we will refer to as group M (Major group). The HIV-1 group O is currently emerging in western central Africa but its spread in Europe has already started.

Acquired Immunodeficiency Syndrome↗